There are numerous examples of hand-held electronic devices which include a housing surrounding internal circuitry and a battery power supply. The housing also mounts an input, typically a keypad, and a display screen output. Examples include calculators, navigational aids such as global positioning systems, video games, inventory tracking equipment, etc. These devices are often held in one hand while the other hand is used to operate the input, such as by pushing the keys of the keyboard.
With miniaturization of components, the size of such devices (i.e. height, width and thickness) is often not determined by the internal components, but by human factors. In other words, the housing may be larger than strictly necessary to house the internal components. This is to allow the input to be of a size easily used by human fingers, the display screen to be of a size easily read by the human eye, and the overall housing to be of a size and shape easily held in the human hand. With increased computing power available through contemporary integrated circuits, the display screen is more and more a relatively large graphics display, rather than the previous 8 to 10 digit display.
Despite this relative freedom of design, prior art hand-held devices have been awkward to operate. As noted above, they were often used by holding the device in one hand while operating the input with the other hand. However, it is often desirable to hold and operate such devices with a single hand, to free the other hand for another task. Where this is the case, the user supports the device from behind with the fingers and outer end of the palm, with the thumb wrapped about the device. In this manner the heel of the palm serves to clamp the device to the hand, and the thumb may be used to operate the input.
While this is serviceable, this often results in unstable and awkward use. First, in many prior art devices the various faces forming the rectangular device are connected by small radius curves, such that relatively sharp corners are formed. This make the devices relatively difficult and uncomfortable to hold in the hand. Second, while these devices have a width which permits them to be held in a single hand, they are often too wide to permit the thumb to reach fully across the input while held securely in the hand. This renders the device unusable with a single hand, or forces the user to hold the device in an unstable manner.
Finally, it is a standard arrangement to mount the screen vertically above (with respect to the user's vision) the input. As noted above, for single-handed operation the device must be located in the hand with the input adjacent the thumb for operation. Since many devices have a height and width which is nearly fully occupied by the input and display, this typically results in a much larger portion of the device extending outwardly above the fingers (in the generally vertical direction) than extends below the thumb across the fingers. This can cause an unstable arrangement, with it being difficult to maintain the device secure with only the fingers and heel of the palm.
Beyond these factors, prior art devices have often been rather delicate, in that they have not been sufficiently weatherproofed. This of course limits their applications. The housing of prior art devices have employed two or more main shell sections which are secured together. Providing seals between these shell sections has been relatively straightforward. However, these devices also carry battery power supplies which must be accessible to the user. Prior art arrangements have resulted in battery storage compartments having relatively large covers, which in turn require relatively large seals. Such relatively large seals are difficult to maintain throughout the life of the device.